![Recursive
Functions
-module(recursive).
-export([fact/1, qsort/1]).
fact(1) -> 1;
fact(N) -> N * fact(N - 1).
qsort([]) -> [];
qsort([H | T]) ->
qsort([X || X <- T, X < H])
++ [H] ++
qsort([X || X <- T, X >= H]).
• Recursive.erl
• Compile/Run
13](https://image.slidesharecdn.com/erlangos-200211144837/85/Erlang-os-13-320.jpg)
![Guarded Commands
• Compare.erl
-module(guarded).
-export([gt/2]).
greaterThan(N, M) ->
if N > M -> true;
N < M -> false;
true -> equal
end.
while(N) when N == 5 ->
io:fwrite("~n~B ",[N]), while(N-
1);
while(N) when N > 0 ->
io:fwrite("~B ",[N]), while(N-1);
while(_) when true ->
done.
• Compile/Run
14](https://image.slidesharecdn.com/erlangos-200211144837/85/Erlang-os-14-320.jpg)
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Erlang os
- 1. ERLANG Operating Systems PST22211- 2020 Dilshan Chathuranga Hashani Sandunika Ishan Suranga Maduka Shashikani Minoli Sachinthana Osuri Dishmini Pinindu Chethiya Sandunika Hashani Thisaru Dhanushika Yalini Pushpakanthan 01
- 3. In a nutshell, what is Erlang? Erlang is a general-purpose programming language and runtime environment. Erlang has built-in support for concurrency, distribution and fault tolerance. Erlang is used in several large telecommunication systems from Ericsson. Erlang is available as open source from http://www.erlang.org. 03
- 4. The Founder Along with Robert Virding and Mike Williams in 1986, Armstrong develo ped Erlang, which was released as o pen source in 1998. Joseph Leslie Armstrong (27 December 1950 – 20 April 2019) was a computer scientist working in the area of fault – tolerant distributed systems. He is best known as one of the co-designers of the Erlang programming language. Joe Armstrong 04
- 5. What is it ?? ----------------------------------------------------- • Erlang was designed with the aim of improving the development of telephony applications. ------------------------------------------------------ • The initial version of Erlang was implemented in Prolog and was influenced by the programming language PLEX used in earlier Ericsson exchanges. ------------------------------------------------------ • In 1992, work began on the BEAM virtual machine (VM) which compiles Erlang to C using a mix of natively compiled code and threaded code to strike a balance between performance and disk space. ------------------------------------------------------ • According to Armstrong, the language went from lab product to real applications following the collapse of the next-generation AXE telephone named AXE-N in 1995. The name Erlang, attributed to Bjarne Däcker, has been presumed by those working on the telephony switches (for whom the language was designed) to be a reference to Danish mathematician and engineer Agner Krarup Erlang and a syllabic abbreviation of "Ericsson Language". 05
- 6. • As a result, Erlang was chosen for the next Asynchronous transfer mode (ATM) exchange AXD. • In 1998 Ericsson announced the AXD301 switch, containing over a million lines of Erlang and reported to achieve a high availability of nine “9” s. • Shortly thereafter, Ericsson Radio Systems banned the in-house use of Erlang for new products, citing a preference for non- proprietary languages. The ban caused Armstrong and others to leave Ericsson. • The implementation was open-sourced at the end of the year. Ericsson eventually lifted the ban and re-hired Armstrong in 2004. • In 2006, native symmetric multiprocessing support was added to the runtime system and VM. 06
- 7. Timeline of Erlang Ericsson CS Lab formed 1984 1987 1991 1993 1994 1996 First fast Implementation First Product Early Erlang Prototype Distributed Erlang Open telecom platform 1998 Become open Source Future 07
- 8. #Facts Contents Title • In 2014, Ericsson reported Erlang was being used in • its support nodes, and in GPRS ,3G and LTE mobile networks worldwide and also by Nortel and T-Mobile. • As Tim Bray, director of Web Technologies at Sun Microsystems, expressed in his keynote at O’Reilly Open Source Convention (OSCON) in July 2008: • If somebody came to me and wanted to pay me a lot of money to build a large scale message handling system that really had to be up all the time, could never afford to go down for years at a time, I would unhesitatingly choose Erlang to build it in. • Erlang is the programming language used to code Whatsapp. Contents Title Contents Title 08
- 9. Erlang Features • Concurrency • Fault tolerance • Soft – Real time • Distribution • Hot code loading • External Interfaces • Platform Independent 09
- 10. Data Types • Numbers: Integers and floats • Atoms – similar to constants (true and false are atoms) • Funs – anonymous functions • Sum = fun(X,Y) -> X+Y end. • Sum(5,5) • Tuples – Fixed amount of data. Any item can be accessed in constant time • Lists – Group of data types; varying amount. First item can be accessed in constant time, while other elements can be accessed in O(n) time. • Records – similar to structs in c 10
- 11. Syntax 11
- 12. Syntax Hello World You can simply impress your audience and add a unique zing and appeal to your Presentations. Content Here 12
- 13. Recursive Functions -module(recursive). -export([fact/1, qsort/1]). fact(1) -> 1; fact(N) -> N * fact(N - 1). qsort([]) -> []; qsort([H | T]) -> qsort([X || X <- T, X < H]) ++ [H] ++ qsort([X || X <- T, X >= H]). • Recursive.erl • Compile/Run 13
- 14. Guarded Commands • Compare.erl -module(guarded). -export([gt/2]). greaterThan(N, M) -> if N > M -> true; N < M -> false; true -> equal end. while(N) when N == 5 -> io:fwrite("~n~B ",[N]), while(N- 1); while(N) when N > 0 -> io:fwrite("~B ",[N]), while(N-1); while(_) when true -> done. • Compile/Run 14
- 15. Who use Erlang 146 companies reportedly use Erlang in their tech stacks, including WhatsApp, Heroku, and thoughtbot. 15
- 16. Erlang Integrations Rollbar, Google Code Prettify, Airbrake, Tile38, and Leptus are some of the popular tools that integrate with Erlang. Here's a list of all 7 tools that integrate with Erlang. 16
- 17. Pros & Cons Pros • Simplicity this is one of the most valuable characteristics of a language.it has a very small set of syntactic primitives that can use. Even the concurrent aspect of the language is done using just plain functions (with the exception of the receive primitive). Erlang's simplicity also makes it very understandable and fun to work with. • Managing Concurrency & Failure Erlang concurrent programs can be built, scaled and distributed with ease. Once you have the deployment and integration set up, scaling Erlang nodes and spawning new Erlang processes on different machines becomes easy. Erlang standard library provides easy-to- use functions for this very purpose, so reaching parallelism is not only cheap in terms of implementation but also elegant. 17
- 18. • When it comes to program failures Erlang also has your back. When spawning new processes you are guaranteed to be notified about it to all the monitors and links that were established. This allows to re-spawn any failed process automatically, which is already part of the OTP standard library and the default way for structuring Erlang applications. Mature community • One of the most important aspects to consider when trying to predict a technology's future is to check the what kind of community that technology is being supported and used by. We've all seen good technologies that end up being destroyed with useless and buggy features; this is usually what a toxic community does. • Erlang's community is small, mature and simplicity-driven, which protects it from being destroyed. This is why Erlang benefits and robustness has lasted this long. 18
- 19. Pros & Cons Cons Setup Setting up, provisioning and deploying Erlang applications can be hard to understand and cumbersome. This is due to many reasons, one of the most important ones being the lack of a proper and unique package manager. Also, the hot-reloading feature that Erlang provides by default is no longer applicable is nowadays containerization of applications. Instead of having to upload the new code and triggering a hot-reload, you would just start up an new container and stop the one that's currently running. The Docker-way of doing things differs a bit from the Erlang-way, so in some cases, you may have to apply some hack-ish behavior for deployments. Types Erlang is a dynamically-typed language, meaning that during the compilation phase you won't get any type errors. Erlang's robustness and failure handling makes errors during runtime a lot less costly. 19
- 20. Conclusion All-in-all, Erlang does an almost-perfect job at handling concurrency and the complexity involved when dealing with it, including error handling, concurrency guarantees and architectures robustness. Even though it lacks some very useful features used by many programming languages like a proper package manager and a static type-checker, it does not obfuscate its benefits. Erlang might not be the right tool for every project, but it's definitely very practical and safe working with it which makes it worth considering it. 20